The tracks of track-laying vehicles have always presented a problem in that track tension should be great enough to minimize throwing off the track, but not unnecessarily great because the greater the tension in the track is, the greater is the load on the bearings of the wheels which pull the track tight.
Experience can be relied on to determine optimum tension in a given track system. The problem then becomes one of measuring track tension in a reliable way so that adjustments may be made in track tension to keep the tension close to its optimum value.
Heretofore, it has been the practice to measure track sag (catenary displacement from a straight line) between a selected pair of adjacent rollers. However, such a measurement method is inaccurate and unreliable, especially under field conditions.